1. Field of the Invention
This invention relates to a system and a method for rotary plastic blow molding with in-mold labeling.
2. Background Art
In-mold labeling has previously been performed with rotary wheel type blow molding machines as disclosed by U.S. Pat. Nos. 4,479,770 Slat et al.; 4,639,207 Slat et al; 4,680,000 Nowicki et al.; 4,834,641 Keyser; 4,909,723 Slat et al.; 4,973,241 Keyser; 5,044,922 Plenzler et al.; 5,104,306 Gordon et al.; and 5,266,149 Collette et al.
Such in-mold labeling is performed by inserting a label within an open mold as the open mold is moved with other molds on a rotary wheel prior to the mold closing about an extruded plastic tube or about a hot plastic preform, whereupon blow molding of the extruded plastic tube or the preform bonds the label within the mold to the plastic and provides a smooth transition between the label and the adjacent blow molded surface. In addition to strengthening the blow molded container that results from this process, the more conventional post blow molding label application operation is eliminated.
In certain rotary blow molding machines, the production is very high, e.g., thousands of containers per hour and some as high as more than fifty thousand containers per hour with injection stretch blow molding machines that blow mold preforms as opposed to the extruded parison type of blow molding. Such high production rates make it difficult to place a label within the mold prior to the blow molding since there is little time to do so during the fraction of a second available to deposit the label within the mold.
Also, rapid in-mold labeling is made more difficult because label magazines in which the labels are stored normally are not capable of delivering the labels at a greater rate than about 60 to 70 labels per minute. Label stacks in which the labels are stored prior to being removed by vacuum pickup dispensing heads do not allow the labels to move away from the stack at a greater rate because air cannot normally move behind the labels fast enough to permit removal of more than 60 to 70 or so labels per minute.
Other prior art label systems noted during an investigation conducted in connection with the invention include U.S. Pat. Nos. 3,575,409 Calvert and 4,293,365 Geyser et al.
An object of the present invention is to provide an improved system for rotary plastic blow molding with in-mold labeling.
In carrying out the above object, a plastic blow molding machine of the system has a rotary mold wheel that supports a plurality of molds for rotary movement along a rotary path about a mold wheel axis and for concomitant pivotal movement of mold sections of the molds between open and closed positions about associated mold axes that extend parallel with the mold wheel axis and with the mold sections opening in an outward direction from the mold wheel axis and symmetrically about associated mold parting planes that extend from the mold wheel axis through the associated mold axes. An in-mold labeler of the system includes a dispensing assembly including a base and a dispensing wheel that is rotatably mounted on the base about a dispensing wheel axis that extends parallel to the mold wheel axis. The dispensing wheel includes a plurality of dispensing head assemblies each of which includes a support and a dispensing head mounted on the support for movement along a dispensing head axis of the support between pick and place positions. Each dispensing head includes at least one label carrier for receiving a label in the pick position thereof and for transferring the label in the place position thereof to an adjacent mold of the blow molding machine. An actuator of the in-mold labeler moves the support of each dispensing head assembly during a label depositing operation along the rotary path of the adjacent open mold about the mold wheel axis and for angularly positioning the support of the dispensing head assembly about a support axis such that the dispensing head axis moves in alignment with the moving mold parting plane of the adjacent open mold as the dispensing head is moved on the support during the label depositing operation from the pick position to the place position to deposit the label within the adjacent open mold in a manner that permits high speed operation of the in-mold labeling. Label transfer apparatus of the system includes a transfer head that is movable adjacent a label magazine which stores a stack of labels with an exposed end from which the labels are subsequently dispensed. The transfer head includes a vacuum opening through which a vacuum is supplied. An actuator of the apparatus moves the transfer head with a rolling motion to engage the vacuum opening with the label at the exposed end of the label magazine and to initially pull an extremity of the label away from the label stack and thereby permit air to move behind the label, to subsequently pull an intermediate portion of the label away from the label stack and thereby permit more air to move behind the label, and to finally pull an opposite extremity of the label away from the label stack in a manner that permits high speed labeling as the label is subsequently transferred from the transfer head to the in-mold labeler for the in-mold labeling of the plastic blow molding machine.
The actuator of the in-mold labeler includes a first cam mechanism that moves each dispensing head during the label depositing operation along the rotary path of the adjacent open mold. The in-mold labeler actuator also includes a second cam mechanism that angularly positions the support of the dispensing head assembly about the support axis such that the dispensing head thereof moves in alignment with the moving mold parting plane of the adjacent open mold as the dispensing head is moved on the support during the label depositing operation from the pick position to the place position to deposit the label within the adjacent open mold in a manner that permits the high speed operation of the in-mold labeling. The label transfer apparatus includes a rotary table that supports the label transfer head for rotary movement with the table adjacent the label magazine and for rotary movement with respect to the table under the impetus of the label transfer actuator to provide the rolling motion that pulls the label from the label magazine.
The dispensing wheel of the in-mold labeler includes a plurality of tracks that extend radially from the dispensing wheel axis and are respectively associated with the dispensing head assemblies. Each dispensing head assembly is mounted on the associated tracks for movement under the control of the first cam mechanism, and each dispensing head assembly includes a pivotal mount that mounts the support thereof for pivotal movement about the associated support axis under the control of the second cam mechanism. The label transfer apparatus preferably includes a plurality of the label transfer heads supported on the rotary table for rotary motion on the table adjacent the label magazine and for rotary movement with respect to the table under the impetus of the label transfer actuator.
A third cam mechanism of the in-mold labeler includes an operator for moving each dispensing head with its label carrier on the associated support between the pick position and the place position where the label carrier is positioned within the adjacent open mold to transfer the label carried thereby to the mold. The actuator of the label transfer apparatus includes a rotary actuator member that rotates about a central rotary axis of the rotary table and also includes an endless belt that extends from the rotary actuator member to the label transfer heads to provide the rotation thereof with respect to the rotary table.
The label carrier of each dispensing head is mounted on the dispensing head for movement between a retracted position and a label transfer position. The third cam mechanism includes a cam member that is mounted on the base of the dispensing assembly and also includes an operator that is operable to move the cam member toward and away from the blow molding machine. The cam member of the third cam mechanism includes a dispensing cam surface and also includes a label carrier cam surface. Each dispensing head includes a dispensing head cam follower that is engaged by the dispensing head cam surface of the cam member of the third cam mechanism to move the dispensing head on the associated support between the pick and place positions. Each dispensing head includes a label carrier cam follower that is engaged by the label carrier cam surface of the cam member of the third cam mechanism to move the label carrier between its retracted and label transfer positions with the dispensing head in its place position to transfer the label to the adjacent open mold. The label transfer apparatus has at least one tension wheel mounted on the rotary table with the belt extending thereover to provide tensioning of the belt, and preferably there are a pair of the tension wheels mounted for rotation on the rotary table adjacent the rotary actuator member.
The in-mold labeler includes a lock mechanism for locking the dispensing head from movement on the support of the dispensing head assembly and for locking the label carrier in its retracted position. This lock mechanism includes a cam follower for releasing the lock mechanism and the cam member of the third cam mechanism includes an unlocking cam surface for engaging the cam follower of the lock mechanism to release the lock mechanism and permit movement of the dispensing head on the support between the pick and place positions under the impetuous of the operator and to also permit movement of the label carrier between the retracted and label transfer positions. The label transfer apparatus has each label transfer head on the rotary table provided with a pair of vacuum openings one of which engages the label adjacent its first extremity to initially pull the label away from the label stack and the other of which engages the label adjacent its opposite extremity to finally complete the pulling of the label away from the label stack.
Each dispensing head of the in-mold labeler as disclosed includes a pair of label carriers mounted on the dispensing head for movement between retracted and label transfer positions.
Another object of the present invention is to provide an improved method for blow molding comprising: rotating a mold wheel of a plastic blow molding machine with the mold wheel supporting a plurality of molds for rotary movement along a rotary path about a mold wheel axis and for concomitant pivotal movement of mold sections of the molds between open and closed positions about associated mold axes that extend parallel with the mold wheel axis and with the mold sections opening in an outward direction from the mold wheel axis and symmetrically about associated mold parting lines that extend from the mold wheel axis through the associated mold axes. The method also involves rotating a dispensing wheel of a dispensing assembly of an in-mold labeler about a dispensing wheel axis that extends parallel to the mold wheel axis, with the dispensing wheel including a plurality of dispensing head assemblies each of which includes a support and a dispensing head mounted on the support for movement along a dispensing head axis of the support between pick and place positions, and with each dispensing head including at least one label carrier for receiving a label in the pick position thereof and for transferring the label in the place position thereof to an adjacent open mold of the blow molding machine. The labeling method also involves moving the support of each dispensing head assembly during a label depositing operation along the rotary path of the adjacent open mold about the mold wheel axis and angularly positioning the support of the dispensing head assembly such that the dispensing head axis moves in alignment with the moving mold parting plane of the adjacent open mold as the dispensing head is moved on the support during the label depositing operation from the pick position to the place position to deposit the label within the adjacent open mold in a manner that permits high speed operation of the in-mold labeling. The method also is performed by transferring labels from a label magazine to the dispensing assembly by moving a transfer head adjacent a label magazine which stores a stack of labels with an exposed end from which the labels are subsequently dispensed. A vacuum is drawn through a vacuum opening of the transfer head which is moved with a rolling motion to engage the vacuum opening with the label at the exposed end of the label magazine to initially pull an extremity of that label away from the label magazine and thereby permit air to move behind the label, to subsequently pull an intermediate portion of the label away from the label stack and thereby permit more air to move behind the label, and to finally pull an opposite extremity of the label away from the label magazine in a manner that permits high speed labeling as the label is subsequently transferred from the transfer head to the in-mold labeler for the in-mold labeling of the plastic blow molding machine.
In performing the blow molding method, a first cam mechanism moves each dispensing head during the label deposition operation along the rotary path of the adjacent open mold, and a second cam mechanism angularly positions the support of the dispensing head assembly such that the dispensing head thereof moves in alignment with the moving mold parting plane of the adjacent open mold as the label carrier is moved on the support during the label depositing operation from the pick position to the place position to deposit the label within the adjacent open mold in a manner that permits the high speed operation of the in-mold labeling, and the label transfer head is supported and moved on a rotary table for movement adjacent the label magazine and for rotary movement with respect to the table to provide the rolling motion that pulls the label from the label magazine. In performing the blow molding, the support of each dispensing head is mounted on an associated one of a plurality of tracks that extend radially from the dispensing wheel axis, each dispensing head being controlled by the first cam mechanism, a pivotal mount of each dispensing head assembly mounting the support of the associated dispensing head for pivotal movement about an associated vertical axis under the control of the second cam mechanism, and a plurality of the label heads are supported and moved on the rotary table for movement therewith adjacent the label magazine and for rotary movement with respect to the table to provide the rolling motion that pulls each label from the label magazine.
The blow molding method also utilizes a third cam mechanism including an operator that moves each dispensing head with its label carrier thereon between the pick position and the place position where the label carrier is positioned within the adjacent open mold to transfer the label carried thereby to the mold, and the label transfer head is rotated with respect to the table by a rotary actuator member that rotates about a central rotary axis of the rotary table and by an endless belt that extends from the rotary actuator member to the label transfer heads. Furthermore, the blow molding method also involves moving the label carrier of each dispensing head between a retracted position and a label transfer position, with an operator moving a cam member of the third cam mechanism on the dispensing assembly base toward and away from the blow molding machine, with a dispensing head cam follower of each dispensing head being engaged by a dispensing head cam surface of the cam member of the third cam mechanism to move the dispensing head between the pick and place positions, and with a label carrier cam follower of each dispensing head being engaged by a label carrier cam surface of the cam member of the third cam mechanism to move the label carrier between its retracted and label transfer positions with the dispensing head in its place position to transfer the label to the adjacent open mold, and the endless belt is tensioned by a tension wheel rotatably mounted on the rotary table and with the tensioning of the endless belt preferably provided by a pair of tension wheels rotatably mounted on the rotary table.
The blow molding method also utilizes a lock mechanism that locks the dispensing head from movement on the support of the dispensing head assembly and locks the label carrier in its retracted position. An unlocking cam follower is actuated to release the lock mechanism in performing the method and an unlocking cam surface engages the unlocking cam follower of the lock mechanism to provide the actuation thereof that releases the lock mechanism and permits movement of the dispensing head on the support between the pick and place positions under the impetuous of the operator as well as permitting the movement of the label carrier between the retracted and label transfer positions. A first vacuum opening of the transfer head initially engages the label adjacent a first extremity to initially pull the label away from the label stack and another label opening subsequently engages the label adjacent its opposite extremity to complete the pulling of the label away from the label stack.
In performing the blow molding, a pair of label carriers can be supported for movement on each dispensing head between the retracted and label transfer positions so as to provide a pair of labels to the adjacent open mold during the in-mold labeling operation.
The objects, features and advantages of the present invention are readily apparent from the following detailed description of the preferred embodiment when taken in connection with the accompanying drawings.